perf: use mimalloc as the runner's global allocator

Cargo.toml

@@ -60,6 +60,7 @@ linux-perf-data = { git = "https://github.com/mstange/linux-perf-data.git", rev
 ] } # unreleased main as of 2026-03-19
 debugid = "0.8.0"
 memmap2 = "0.9.10"
+mimalloc = { workspace = true }
 nix = { version = "0.31.3", features = ["fs", "time", "user"] }
 futures = "0.3.32"
 runner-shared = { path = "crates/runner-shared" }
@@ -113,6 +114,7 @@ libc = "0.2"
 log = "0.4.28"
 serde_json = "1.0"
 serde = { version = "1.0.228", features = ["derive"] }
+mimalloc = "0.1"
 ipc-channel = "0.20"
 itertools = "0.14.0"
 rayon = "1.12"

crates/memtrack/Cargo.toml

@@ -40,7 +40,7 @@ byteorder = "1.5"
 rayon = "1.12"
 parking_lot = "0.12"
 typed-builder = "0.23.2"
-mimalloc = { version = "0.1", optional = true }
+mimalloc = { workspace = true, optional = true }
 
 [build-dependencies]
 libbpf-cargo = { version = "0.26", optional = true }

crates/runner-shared/Cargo.toml

@@ -28,6 +28,7 @@ zstd = "0.13.3"
 [dev-dependencies]
 divan = { version = "4.2.0", package = "codspeed-divan-compat" }
 memmap2 = "0.9.10"
+mimalloc = { workspace = true }
 rand = "0.8"
 tempfile = { workspace = true }
 

crates/runner-shared/benches/memtrack_reader.rs

@@ -15,6 +15,9 @@ use runner_shared::measurement_mode::MeasurementMode;
 use runner_shared::runtime_env::RUNNER_MODE_ENV;
 use std::io::Write;
 
+#[global_allocator]
+static GLOBAL: mimalloc::MiMalloc = mimalloc::MiMalloc;
+
 fn main() {
     divan::main();
 }

crates/runner-shared/benches/memtrack_writer.rs

@@ -16,7 +16,8 @@ use runner_shared::artifacts::{
 /// there anyway.
 #[cfg(not(codspeed))]
 #[global_allocator]
-static ALLOC: divan::AllocProfiler = divan::AllocProfiler::system();
+static ALLOC: divan::AllocProfiler<mimalloc::MiMalloc> =
+    divan::AllocProfiler::new(mimalloc::MiMalloc);
 
 fn main() {
     divan::main();

src/main.rs

@@ -1,3 +1,7 @@
+// musl's allocator is slow on the many small allocations made when decoding memtrack artifacts.
+#[global_allocator]
+static GLOBAL: mimalloc::MiMalloc = mimalloc::MiMalloc;
+
 use codspeed_runner::{clean_logger, cli};
 use console::style;
 use log::log_enabled;